User:Katstudies/Decapacitation factor


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Decapacitation factor (DF) is composed of sperm surface-associated proteins which modulate the fertilizing ability of spermatozoa. Decapacitation is reversible process that converts fertile, capacitated sperm to less-fertile uncapacitated sperm. This is achieved by interaction between cholesterol, phospholipids and fibronectin-like substances and delivered via small vesicles in seminal plasma. DF prevents the onset of capacitation.


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 * Added a definition for decapacitation, which these factors are involved in
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Many DFs are released in secretions from the epididymis and accessory organs of the male reproductive system. However, some DFs have been identified that are located on the acrosome of sperm. Normally, capacitation is initiated through the loss of DF before the spermatozoa can perform the acrosomal reaction. Physiologically, decapacitation will inhibit the acrosomal reaction as DFs reassociate onto the sperm surface. For example, one way this can be achieved through spermatozoal membrane stabilization by maintaining a high physiological cholesterol/phospholipid ratio.

The study of DF is essential to understand unexplained male infertility and has possible role in reversible male contraception. DFs are potent, but can be removed from sperm by gentle centrifugation to produce extremely fertile sperm. DFs have been found in bull, rabbit, boar, stallion, monkey, mouse , and human semen. Purification to obtain DFs and subsequent injection into a uterus with capacitated sperm decreases the efficiency of fertilization and converts sperm to an uncapacitated form. In natural conditions, the uterus has the ability to inactivate or remove DF, allowing capacitation to occur. In vitro incubation of DF with β-amylase was demonstrated to destroy DF activity, and Dukelow hypothesized that uterine amylase would similarly be able to destroy DF activity and allow capacitation to occur.
 * Added sentences that clarify where the DFs are made and their function -- with a contrast between capacitation and decapacitation
 * Kept sentence on cholesterol/phospholipid ratio, however no strict source was found that states this -- Nixon paper suggests that the release of cholesterol supports capacitation by allowed for reversible expansion of the lipid bilayer, increasing stability.


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 * Did not find evidence for the "In vitro incubation of DF with uterine fluids has been reported to have failed to destroy DF activity." but found evidence about in vitro incubation with beta-amylase that connected to uterine amylase.

Various DFs are been found and characterized. One DF was removed by gentle centrifugation from rabbit seminal plasma and is an anionic polypeptide with an MR ~40,000 and is heat stable, cannot be destoroyed by proteases at pH 8, and is stable when incubated other enzymes like lysozyme and glucose oxidase. Some other DFs, such as DF10 and DF-R, have been reported as alternative forms of other proteins found in sperm. NYD-SP27 is a unique DF as it is intrinsic to the sperm acrosome and inhibits the action of phospholipase C that is necessary for capacitation. SERPINE2 is a proposed DF, as it is present in high concentrations on uncapacitated sperm and is lost during the capacitation process. Platelet-activating factor acetylhydrolase is another proposed DF due to the negative correlation between its concentration and the motility of sperm.


 * Added sources and more examples of DFs

//Copy of article to reference as revisions are made is found below

Decapacitation factor (DF) is composed of factors in seminal plasma which modulates the fertilizing ability of spermatozoa. The activity is achieved by interaction between cholesterol, phospholipids and fibronectin-like substances and delivered via small vesicles in seminal plasma. DF prevents onset of capacitation.

Physiologically it is achieved through spermatozoal membrane stabilization by maintaining physiological cholesterol/phospholipid ratio. The study of DF is essential to understand unexplained male infertility and has possible role in reversible male contraception. Ejaculates from animals when purified have obtained DF. Such ejaculates when injected into the uterus with sperms decrease the fertilization by decreasing efficiency of capacitation of spermatozoas.

In natural conditions, uterus have the ability to inactivate or remove overwhelmed DF, serving a purpose. In vitro incubation of DF with uterine fluids has been reported to have failed to destroy DF activity. The DF factors can be removed from the seminal plasma by gentle centrifugation and can be added back. Some known DF and their study have shown to be anilinic polypeptide with MR~40,000, stable to heating at relatively high temperature and stable to enzymes and pH.